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Which 700 R4 Trans?

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Old 09-13-2017, 04:25 PM   #1
corvettehoyt78
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Default Which 700 R4 Trans?

Hello
I`m planning on installing an overdrive (700R4) trans in my 1978
Silver Anniversary) Vette. Does any one know which years are the best
Years for this trans swap ? My car has a 3:70 gear. Will I have to change the trans crossmember, and flex-plate?
Thanks for any info
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Old 09-13-2017, 04:44 PM   #2
TimAT
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I would go with an 89 or later. Those later years, they already have the better rear planetary gearsets, and an aux valve body for the 4th gear, along with an improved front pump. Several other things can be added from the aftermarket to make them even better.
Might need to swap the flexplate to fit the convertor.
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Old 09-14-2017, 04:38 PM   #3
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I would go with a 200 4r because smaller and narrower, more likely to fit your car with out busting ***, like my '72 did mine it was a 4 speed and so I am convinced a narrower tunnel than a stock auto car would have...

the 700 had me welded up a trans mount to fit the tail shaft....the stock spacing fit the 200 and I did not have to shorten the drive shaft....

200 is a much cheaper/simpler install, just get it built well, or get lucky in a DIY build, with some help from a fellow named TimAT......
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Old 09-14-2017, 09:38 PM   #4
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Instead of used tranny it is better to buy one from one of the better online shops that build them. don't buy anything rated at less than 500HP

The flex is the same.

Buy a correct cross member like from Bowtie OD. That eliminated the exhaust problems of going through the cross X. I made a pass under cross member 30 years ago and it is still running strong
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Old 09-15-2017, 06:55 PM   #5
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Truly not that much difference between the years. The earliest of models probably have already had upgraded input drum, input sprag and pump installed by now.

'87 was the first year of the Hydramatic version. A forward accumlator was added to cushion the shift from neutral to drive, cushion spring added to the low reverse clutch pack, aluminum piston added to the reverse input drum, more vanes in the pump and a revised stack in the 3-4 clutches. There were also minor changes to the valve body as they torque converter clutch was computer controlled by then.

Last edited by David Mc; 09-15-2017 at 06:56 PM.
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